The preliminary solution is to use the <ALT><NUM>-combination (NUM keys
are the numbers on the numeric keypad of your keyboard, not the numbers
in the top row). You produce the characters by pressing the <ALT> key
and simultaneously entering the ASCII-code denoting the characters you
want to produce as follows:

<ALT><91> : [
<ALT><93> : ]
<ALT><123> : {
<ALT><125> : }

Unfortunately, "²" (like in R²) can't be produced in this way, but this
is not vital.

For users using keyboards of notebooks with not separate numeric keypad
this is a bit more difficult because they have to switch on the "keypad"
by using special function keys, enter the code, and have to switch back
to normal.

This is a preliminary solution; as I understood, programmers at
StataCorp are busy solving the problem.

BTW: Those who are using Friedrich Huebler's AutoIt scripts (rundo.au3
or rundolines.au3) should note that in Stata 12 the shortcut to activate
the command window has changed from <CTRL><4> to <CTRL><1>. To make use
of the scripts the command -Send("^4")- has to be changed to
-Send("^1")- (twice in each script).